package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 * @author DJ
 * @description
 * @date 2022/11/28 下午11:10
 **/
@Component
public class RedisIdWorker {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    /**
     * 开始时间戳
     */
    public static final long BEGIN_TIMESTAMP = 1640995200L;

    /**
     * 序列号的位数
     */
    public static final int COUNT_BITS = 32;

    /**
     * 构造方法方式注入
     */
    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 获取全局id
     *
     * @param keyPrefix 前缀
     * @return long
     * @author DJ
     * @date 下午11:35 2022/11/29
     **/
    public long nextId(String keyPrefix) {
        // 生成时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        long timeStamp = nowSecond - BEGIN_TIMESTAMP;
        // 生成序列号
        // - 1.获取当前日期，精确到天（1.避免id数过大 2.方便统计）
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        // - 2.自增长
        Long count = stringRedisTemplate.opsForValue().increment("incr:" + keyPrefix + ":" + date);
        // 拼接返回 利用 位运算+或运算
        return timeStamp << COUNT_BITS | count;
    }
}
